1. Field of the Invention
The present invention relates to an image forming apparatus that forms color images on recording materials.
2. Description of the Related Art
Image forming apparatuses such as electrophotographic copiers and printers use a transfer unit to transfer a toner image borne on a photosensitive drum or an intermediate transfer member serving as an image bearing member, to a recording material. A fixing apparatus (fixer) then heats and presses the recording material to heat and fix the unfixed toner image to the recording material.
In the fixing apparatus, as the image forming apparatus is used over time, significant amounts of toner on the unfixed toner image or paper dust from a recording paper as a recording material may adhere to the outer peripheral surface (surface) of any component roller to contaminate the component roller surface. The adhesion results from an electrostatic offset caused by a charged recording material or component roller, a thermal offset caused by excessive or insufficient fixation, adhesion of the unfixed toner to the component roller surface during an operation of removing a jammed recording material, or paper dust falling from a recording material with a low surface strength. Upon exceeding the limit of accumulation on the surface of the component roller, the dirt or dust on the component roller surface is ejected onto the recording material through a nip portion to contaminate and damage the image on the recording material. Furthermore, the contamination of the component roller surface causes the recording material to be easily wound around the component roller surface. This may result in a jam in the fixing apparatus or damage to the component roller.
To solve these problems, the present applicant has proposed an image forming apparatus configured to clean the contaminated surface of a component roller (Japanese Patent No. 2651232). The image forming apparatus produces, as a cleaning sheet, a recording material with a toner pattern formed thereon and dedicated to cleaning. The image forming apparatus re-feeds the cleaning sheet so that the toner pattern on the cleaning sheet comes into contact with the component roller to be cleaned. The component roller surface is thus cleaned.
If a recording material containing a large amount of filler such as calcium carbonate or talc is passed through (introduced into) the nip portion, the filler adheres to the component roller surface to degrade the releasability of the component roller surface. Thus, the contamination of the component roller surface with toner or paper dust is rapidly deteriorated, with the level of the contamination increased. Under these conditions, even though the above-described cleaning is performed, the contamination of the component roller surface may not be easily removed by one cleaning operation.
To solve these problems, a plurality of pages of cleaning sheets may be passed through the nip portion or the cleaning operation may be frequently performed. However, undesirably, this may hinder normal image formation (printing) over a long time, or many recording materials may need to be used for the cleaning action.